Novel carbon nanofiber and method of manufacture

ABSTRACT

A method of producing carbon nanofibers is disclosed that substantially impacts the carbon nanofibers&#39; chemical and physical properties. Such carbon nanofibers include a semi-graphitic carbon material characterized by wavy graphite planes ranging from 0.1 nm to 1 nm and oriented parallel to an axis of a respective carbon nanofiber, the semi-graphitic carbon material also being characterized by an inclusion of 4 to 10 atomic percent of nitrogen heteroatoms, the nitrogen heteroatoms including a combined percentage of quaternary and pyridinic nitrogen groups equal to or greater than 60% of the nitrogen heteroatoms. The method of manufacture includes, for example, preparing a Polyacrylonitrile (PAN) based precursor solution, providing the PAN-based precursor solution to a spinneret and then performing an electro-spinning operation on the PAN-based precursor solution to create the one or more PAN-based nanofibers. The electro-spinning operation includes passing the PAN-based precursor solution from the spinneret to a collector at a distance between 1 cm to 30 cm while providing an Alternating Current (AC) voltage between the spinneret and the collector, the AC voltage including a frequency ranging from 20 Hz to 100,000 Hz and either a Peak-to-Peak (P-P) voltage ranging from 100 V to 30,000 V or a Root-Mean-Square (RMS) voltage ranging from 100 V to 30,000 V. Afterwards, post-electro-spinning operations, stabilizing treatments and pyrolysis treatments are performed.

BACKGROUND I. Field

This disclosure relates to carbon nanofibers having novel andadvantageous properties. This disclosure also relates to methods ofmanufacturing such carbon nanofibers.

II. Background

Carbon is among a few elements having a high level of chemical bondingflexibility. This flexibility lends itself to the formation of a largevariety of allotropes including diamond, graphite, and fullerenes which,while all being composed essentially of elemental carbon, vary widely intheir properties. One particular relevant field of interest is theformation of Carbon NanoFibers (CNFs) and Carbon NanoTubes (CNTs). WhileCNFs and CNTs are both nanometer in scale and produced in similarmanners, there are distinct differences that impact theirmanufacturability and chemical and physical properties. However, thecomplete range of different CNT and CNF materials has not been fullyexplored.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and nature of the present disclosure will become moreapparent from the detailed description set forth below when taken inconjunction with the accompanying drawings in which referencecharacteristics identify corresponding items.

FIG. 1 is a flowchart outlining an exemplary operation for manufacturinga novel Carbon NanoFiber (CNF).

FIG. 2 depicts an example of an electro-spinning device usable toproduce the novel CNF discussed with respect to FIG. 1.

FIG. 3 depicts a variant of the electro-spinning device of FIG. 2, whichis also usable to produce the novel CNF discussed with respect to FIG.1.

FIGS. 4A-4K depict various electrode configurations for the electrodesshown in FIG. 3.

FIG. 5 provides visual representations of the novel CNFs produced by themethods and systems of this disclosure.

FIG. 6 provides a visual contrast of the novel CNFs produced by themethods and systems of this disclosure against other carbon-basedmaterials.

FIG. 7 provides series of visual representations of the novel CNFsproduced by the methods and systems of this disclosure from themacro-scale to an atomic scale.

DETAILED DESCRIPTION

The disclosed methods and systems below may be described generally, aswell as in terms of specific examples and/or specific embodiments. Forinstances where references are made to detailed examples and/orembodiments, it should be appreciated that any of the underlyingprincipals described are not to be limited to a single embodiment, butmay be expanded for use with any of the other methods and systemsdescribed herein as will be understood by one of ordinary skill in theart unless otherwise stated specifically.

The following special definitions apply for this disclosure.

The term “appreciable” refers to some quality, e.g., a particular amountor percentage, of something that results in a detectable differenceeither from a defined base-line or over prior-art materials. Suchquality should be detectable either directly through observation, e.g.,through a Scanning Electron Microscope (SEM) or a Transmission electronmicroscope (TEM), or indirectly through physically and/or chemicallydetectable properties, e.g., electron mobility, conductivity, etc.

The term “about” refers to variations expected in industrialmanufacturing equipment for CNFs that may vary for different forms ofequipment. For example, it is expected that even the most expensivehigh-voltage equipment will likely produce voltage outputs that vary afew percent.

The term “about” also refers to variations in an end product that areexpected to occur even when reasonable quality controls are employed.

The term “Stress Activated Pyrolytic Carbon,” or “SAPC,” refers to thenovel composition based on carbon and nitrogen that is the subject ofthis disclosure. SAPC, by the definition of this disclosure, refers toan inclusion of a semi-graphitic carbon material characterized by wavygraphite planes ranging from 0.1 nm to 1 nm and oriented parallel to anaxis of a respective carbon nanofiber. The term “oriented parallel”refers to the general direction of a main surface of a particulargraphitic plane and takes into account that variations in angle areexpected to occur based on the “wavy” physical nature of SAPC.

The semi-graphitic carbon material of this disclosure is alsocharacterized by an inclusion of 4 to 10 atomic percent of nitrogenheteroatoms with the nitrogen heteroatoms including a combinedpercentage of quaternary and pyridinic nitrogen groups equal to orgreater than 60% of the nitrogen heteroatoms. However, it is to beappreciated that various “levels of SAPC quality” may be obtained usingvariations within the prescribed limits and ranges of the disclosedmethods and systems, and that a “level of SAPC quality” as used in thisdisclosure refers to a minimum combined percentage of quaternary andpyridinic nitrogen groups of the nitrogen heteroatoms.

For example, one particular “level of SAPC quality” may refer to thecombined percentage of quaternary and pyridinic nitrogen groupsexceeding 70%, a second particular “level of SAPC quality” may refer tothe combined percentage of quaternary and pyridinic nitrogen groupsexceeding 80%, and a third particular “level of SAPC quality” may referto the combined percentage of quaternary and pyridinic nitrogen groupsexceeding 90%.

The lowest SAPC quality is to be considered an “appreciable,” i.e.,detectable, combined percentage of quaternary and pyridinic nitrogengroups. However, the lowest SAPC quality of interest is not expected tobe less than 60%.

Testing by the inventors of the disclosed method and systems indicatesthat the uppermost range of SAPC quality according to thepresently-disclosed methods and systems exceeds 90%.

FIG. 1 is a flowchart outlining an exemplary operation for manufacturinga novel SAPC-based Carbon NanoFibers (CNFs).

The process starts in step S110 where a precursor solution is prepared.The particular precursor solution in the present embodiment is aPolyacrylonitrile (PAN) based precursor solution that includes: (1) PANhaving a molecular weight ranging from 100,000 to 500,000, and (2) asuitable solvent having less than 5% water by weight.

The PAN-based precursor solution of the present example includes 6% to20% PAN by weight in the solvent. However, in varying embodiments theexact percentage of PAN to solvent may vary beyond the 6% to 20% rangeused in the present example.

Possible solvents include, for example, Dimethylsulfoxide (DMSO),Dimethylformamide (DMF) and Propylene Carbonate (PC). However, acombination of any two or more of DMSO, DMF or PC may also be used.Further, other solvents and precursors than those expressly describedabove may be used at a possible reduction in the quality of end product.

Preparing the PAN-based precursor solution includes dissolving the PANin the solvent via a convective mixing operation at a temperatureranging from 25° C. to 130° C. until the PAN is completely dissolved.Alternatively, the PAN-based precursor solution may be mixed for a settime period ranging from, for example, one hour to one week while at thepreviously-described temperature range.

Next, in step S120, the PAN-based precursor solution is provided to aspinneret, and in step S130 an electro-spinning operation is performedon the PAN-based precursor solution to create one or more PAN-basedfibers.

Referring to FIG. 2, an example of an electro-spinning device usable toproduce the SAPC-based CNFs is disclosed. The electro-spinning deviceincludes a precursor container 210, a pump 212, a Direct Current (DC)voltage source 220, an Alternating Current (AC) voltage source 222, anenclosure 230 and an external drum 252. The enclosure 230 has disposedwithin a spinneret 240 and a collector drum 250 surrounded by anatmosphere 232.

The example spinneret 240 of FIG. 2 is a needleless (i.e., nozzle)device. While needleless spinnerets can take many forms, needlelessspinnerets are often categorized into two forms: stationary androtating. For example, in one embodiment, a needleless spinneret cantake the form of a stationery conductive metal string. In otherembodiments, needless spinnerets can take the form of a drum ordrum-like object that rotate inside a bath of precursor solution.

While the example spinneret 240 of FIG. 2 is needleless, in still otherembodiments any number of needle-type spinnerets may be used, such as asingle needle spinneret, a multiple needle spinneret, and so on. Manyneedle spinnerets are described as “straw-like” while other needlespinnerets are described as “coaxial.” Coaxial spinnerets can produce“core and shell” fibers or even fibers with multiple shells.

In addition to known needle and needless devices, it is envisioned thatthe term “spinneret” can include future-developed needle devices,future-developed needless devices and any other known or later developedtype of spinneret that does not conveniently fit within thecharacterizations of “needle” or “needleless.” By way of example, byproviding an atomized mist of the PAN-precursor into a volume of spaceand then “blasting” the individual PAN-precursor particles constitutingthe mist towards a collector using an appropriate gas or vapor, it ispossible to produce a number fine fibers.

In operation, the pump 212 provides the PAN-based precursor from theprecursor container 210 to the spinneret 240. The spinneret 240, inturn, ejects a plurality of fiber streams 260 to the collector drum 250,and it is at this time that the PAN-based precursor is processed to formPAN-based fibers 262. The resulting combined PAN-based fibers 262 arethen passed to the external drum 252 for collection and storage. Whilethe example spinneret 240 is generally circular and the examplecollector 250 is drum-shaped, it is to be appreciated that theparticular configuration of the spinneret 240 and the collector 250 mayvary as is known to those skilled in the relevant arts.

Within the operation of the embodiment of FIGS. 1-2, the distancebetween the spinneret 240 and the collector drum 250 may varysubstantially to include distances ranging from 1 cm to 30 cm, and inother embodiments the distance between the spinneret 240 and thecollector drum 250 may exceed 30 cm.

As the fiber streams 260 are passed from the spinneret 240 to thecollector drum 250, the DC voltage source 220 and the AC voltage sourceeach provide a differential voltage between the spinneret 240 to thecollector drum 250 in such a way as to materially alter the resultantPAN-based fibers 262.

For example, by providing a DC voltage ranging from about plus or minus1000 V to about plus or minus 30,000 V between the spinneret 240 and thecollector 250 while passing the fiber streams 260, the streams ofPAN-based precursor are drawn to the collector 250 while beingprocessed. In addition, the physical dimensions and shape of theresultant PAN-based fibers 262 may be affected so as to producePAN-based fibers having reduced dimensions. Details regarding an exampleapplication of a DC voltage used in an electro-spinning operation may befound in, for example, Ghazinejad, Holmberg et al, “GraphitizingNon-graphitizable Carbons by Stress-induced Routes” published Nov. 29,2017, by Nature.com (www.Nature.com/scientificreports), the content ofwhich is incorporated by reference in its entirety.

Further, by providing an appropriate AC voltage between the spinneret240 and the collector drum 250, the physical and chemical propertiesunique to SAPC are enabled. In various embodiments, the AC voltage willinclude one or more signals each having: (1) a base frequency rangingfrom 20 Hz to 100,000 Hz, and (2) either a Peak-to-Peak (P-P) voltageranging from 100 V to 30,000 V or a Root-Mean-Square (RMS) voltageranging from 100 V to 30,000 V.

Also in various embodiments, the one or more voltage signals may be anyof a variety of AC signal types, such as a sine wave, a square wave, atriangle wave or combinations thereof.

In other embodiments, however, the AC voltage provided may not bestrictly periodic but may consist of, or include, a random signal, apseudo-random signal or a signal that appears as white noise or filtered(pink) noise.

Returning to FIG. 2, the atmosphere 232 within the container 230 wherethe electro-spinning operation (e.g., step S120) is performed contains avapor of the precursor solution solvent at a temperature ranging from10° C. to 100° C. with a saturation larger than 10%. However, in variousembodiments the minimum saturation may exceed 45% at an ambient (sealevel) atmosphere.

Returning to FIG. 1, after the electro-spinning operation of step 120, apost-electro-spinning operation S130 is performed on the resultantPAN-based fibers. According to the present disclosure, thepost-electro-spinning operation S130 will include both a mechanicaltreatment and a chemical treatment.

The mechanical treatment of the post-electro-spinning operation S130includes hot-rolling and hot-drawing.

The hot-rolling treatment is designed to mechanically compress theresultant PAN-based fibers at a stress ranging from 20 kPa to 2000 kPawhile at temperature ranging from 50° C. to 300° C. However, in otherembodiments the temperature and/or the stress applied may extend beyondtheir respective cited ranges although the quality of the end productmay differ.

The hot-drawing treatment is designed to stretch the one or more fibersfrom 5% to 50% of an original length of the resultant PAN-based fibers.However, as with hot-rolling treatment, the amount of stretching mayexceed the cited range.

The chemical treatment of the post-electro-spinning operation includesdipping the resultant PAN-based fibers in a 5% to 30% hydrogen peroxidesolution followed by removing any remaining solvent and/or any remaininghydrogen peroxide from the resultant PAN-based fibers. However, anychemical treatment suitable to appropriately clean the resultantPAN-based fibers is envisioned.

Continuing, a stabilizing treatment S140 on the PAN-based fibers, whichgenerally involves heating the PAN-based fibers, is performed. Thestabilizing treatment S140 may be performed during or after themechanical treatment of step 130.

If the stabilizing treatment S140 is performed during the mechanicaltreatment, the stabilizing treatment S140 will include heating thePAN-based fibers at a temperature ranging from 200° C. to 300° C. whileperforming the mechanical treatment.

If the stabilizing treatment S140 is performed after the mechanicaltreatment, the stabilizing treatment S140 will include heating the oneor more PAN-based fibers at a temperature ranging from 200° C. to 400°C.

After performing the post-electro-spinning operation and stabilizingtreatment of steps S130 and S140, a pyrolysis treatment S150 on thePAN-based fibers is performed. Generally, the pyrolysis treatment S150will include heating the PAN fibers in an inert atmosphere containingless than one-percent (1%) oxygen, and will include three separateoperations.

The first operation of step S150 involves a heating of the PAN-basedfibers that takes place in an inert atmosphere, preferably anoxygen-free atmosphere, but generally an atmosphere where oxygen doesnot exceed one percent. During the first operation, temperature will bemaintained between 200° C. to 400° C. for a time ranging from one hourto five hours.

The second operation of step S150 also involves a heating of thePAN-based fibers in an inert atmosphere. During the second operation,temperature will be maintained between 600° C. to 2000° C. for a timeranging from one hour to five hours.

The third operation of step S150 is a cooling operation wheretemperature is slowly decreased to room temperature.

It is to be appreciated that, for all three operations of the pyrolysistreatment S150, the temperature ramp rate should not exceed 20°C./minute.

In view of the discussion above, it should be appreciated that thecombined percentage of quaternary and pyridinic nitrogen groups will beaffected by at least: (1) the choice and/or exact composition of polymerprecursor, the AC signal of the electro-spinning operation and theparticular pyrolysis treatment used. Accordingly, appropriate choiceswithin the disclosed ranges will cause the combined percentage ofquaternary and pyridinic nitrogen groups to exceed, for example, 70%,80% and even 90%.

FIG. 3 depicts a variant of the electro-spinning device of FIG. 2, whichis also usable to produce the novel CNFs of this disclosure. In theembodiment of FIG. 3, instead of providing an AC voltage between thespinneret 240 and the collector drum 250, the AC voltage source 222 isused to develop an electric field laterally across the fiber streams260. As shown in FIG. 3, a channel 320 is formed between electrode 321and electrode 322. Accordingly, as the AC voltage source provides an ACelectric field between the electrodes {320, 321}, the fiber streams 260will be affected by the AC electric field as the resultant PAN-basedfibers 262 are produced.

FIG. 4A depicts a view of channel 320 along the length of the channel320 so as to provide a profile of electrode shape. As shown in FIG. 4A,the electrodes {321, 322} of FIG. 3 are plate-shaped. However, as shownin FIG. 4B, the electrodes {321, 322} of FIG. 3 may be substituted withelectrodes {323, 324}, which are curved to form concave arcs towards thechannel 320. Similarly, the electrodes {325, 326} of FIG. 4C may beused, which are curved to form convex arcs towards the channel 320, andas another variant the round wire electrodes {327, 328} of FIG. 4D maybe used.

Turning to FIG. 4E-4K, it is to be appreciated that more than twoelectrodes may be used including the plate-shaped electrodes {441, 442,443}, {444, 445, 446, 447} of FIGS. 4E-4F, the concave-shaped electrodes{451, 452, 453}, {454, 455, 456, 457} of FIGS. 4G-4H, and theconvex-shaped electrodes {461, 462, 463}, {464, 465, 466, 477} of FIGS.4J-4K.

It should be appreciated that, by using three or four electrodes ofvarious configurations, an electric field may be generated that does notoscillate back and forth, but rotates about the center axis of thechannel 320. Additionally, one or more rotating fields may be usedindependently or in combination with one or more alternating fields.

For example, by using the four electrodes {444, 445, 446, 447} of FIG.4F, it is possible to produce a clockwise rotating electric field thatrotates about channel 320 at a rate of 20,000 Hz, a counter-clockwiserotating electric field that rotates about channel 320 at a rate of51,000 Hz, a first oscillating electric field that oscillates betweenelectrodes {444, 446} at a rate of 150,000 Hz, and a second oscillatingelectric field that oscillates between electrodes {445, 447} at a rateof 210,000 Hz.

FIG. 5 depicts an atomic view of SAPC-based carbon fibers. As shown inview 510 of FIG. 5, a microscopic view of a mass of SAPC-based carbonnanofibers produced by the disclosed methods and devices is provided.

In contrast to view 510, in view 520 a Transmission Electron Microscope(TEM) image of SAPC for an exemplary CNF is provided. As shown in view520, the exemplary CNF includes a semi-graphitic carbon materialcharacterized by wavy graphite planes that are generally orientedparallel to an axis of the exemplary carbon nanofiber. While not shownin FIG. 5, X-ray Photoelectron Spectroscopy (XPS) confirms the presenceof graphitic and pyridinic nitrogen groups, which grants SAPC withunique electrocatalysis orders of magnitude greater than similarmaterials.

FIG. 6 provides comparative views of SAPC against other forms of carbon.As shown in view 610, SAPC from a given fiber is shown next to CNTsembedded in the same fiber. CNTs may be made from a similar process asSAPC. However, the substantive differences not only provide CNTs with adifferent chemistry than SAPC, but also cause the CNT fringes to have a“bamboo” shape.

Continuing, as shown in view 620, an amorphous carbon composition, i.e.,carbon nitrides, is provided. Carbon nitrides are similar to carbonblack but include nitrogen groups instead of oxygen. Carbon nitridescome in powder form and, as can be seen in view 620, carbon nitrideplanes are not oriented in any particular direction.

FIG. 7 shows five different views of SAPC. The first view (view 710) isan optical image of a mat of SAPC fibers held by a pair of tweezers. Thesecond view (view 720) shows a microscopic view of individual SAPCnanofibers taken from the mat of SAPC nanofibers of view 710. The thirdview (view 730) is another atomic view of an individual SAPC nanofibertaken using a TEM process.

Continuing, view 740 shows an exemplary structure of several layers ofSAPC with view 750 providing an exemplary molecular structure of aparticular molecule/layer consistent with the above-described structureof SAPC. The redox species used to measure the electrochemical responsein the example of view 750 is ferricyanide. However, any particularredox species, and other redox species, for example, dopamine andiridium hexachloride, can be used.

What has been described above includes examples of one or moreembodiments. It is, of course, not possible to describe everyconceivable combination of components or methodologies for purposes ofdescribing the aforementioned embodiments, but one of ordinary skill inthe art may recognize that many further combinations and permutations ofvarious embodiments are possible. Accordingly, the described embodimentsare intended to embrace all such alterations, modifications andvariations that fall within the spirit and scope of the appended claims.Furthermore, to the extent that the term “includes” is used in eitherthe detailed description or the claims, such term is intended to beinclusive in a manner similar to the term “comprising” as “comprising”is interpreted when employed as a transitional word in a claim.

What is claimed is:
 1. A method of producing one or more carbonnanofibers, the carbon nanofibers including a semi-graphitic carbonmaterial characterized by wavy graphite planes ranging from 0.1 nm to 1nm and oriented parallel to an axis of a respective carbon nanofiber,the semi-graphitic carbon material also being characterized by aninclusion of 4 to 10 atomic percent of nitrogen heteroatoms, thenitrogen heteroatoms including a combined percentage of quaternary andpyridinic nitrogen groups equal to or greater than 60% of the nitrogenheteroatoms, the method comprising: preparing a Polyacrylonitrile (PAN)based precursor solution; providing the PAN-based precursor solution toa spinneret; performing an electro-spinning operation on the PAN-basedprecursor solution followed by pyrolysis of the PAN-based fibers tocreate the one or more carbon nanofibers, wherein the electro-spinningoperation includes passing the PAN-based precursor solution from thespinneret to a collector at a distance between 1 cm to 30 cm whileproviding an Alternating Current (AC) voltage between the spinneret andthe collector, the AC voltage including a frequency ranging from 20 Hzto 100,000 Hz and either a Peak-to-Peak (P-P) voltage ranging from 100 Vto 30,000 V or a Root-Mean-Square (RMS) voltage ranging from 100 V to30,000 V; performing a post-electro-spinning operation on the one ormore carbon nanofibers, the post-electro-spinning operation including amechanical treatment and a chemical treatment; performing a stabilizingtreatment on the one or more PAN-based nanofibers, the stabilizingtreatment including heating the one or more PAN-based nanofibers; andafter performing the post-electro-spinning operation and stabilizingtreatment, performing a pyrolysis treatment on the one or more PAN-basednanofibers, the pyrolysis treatment including heating the one or morePAN-based nanofibers in an inert atmosphere containing less than 1%oxygen.
 2. The method of claim 1, wherein the electro-spinning operationfurther includes providing a Direct Current (DC) voltage between thespinneret and the collector at a distance between 1 cm to 30 cm whilepassing the PAN-based precursor solution from the spinneret to thecollector, the DC voltage ranging from about plus or minus 100 V toabout plus or minus 30,000 V.
 3. The method of claim 2, wherein theelectro-spinning operation is performed in an atmosphere containingvapor of the precursor solution solvent at a temperature ranging from10° C. to 100° C. with a saturation larger than 10%.
 4. The method ofclaim 3, wherein the electro-spinning operation is performed in anambient atmosphere at a temperature ranging from 10° C. to 100° C. withminimum saturation of 45%.
 5. The method of claim 1, wherein thePAN-based precursor solution includes 6% to 20% PAN by weight in asolvent.
 6. The method of claim 5, wherein the solvent includes at leastone of Dimethylsulfoxide (DMSO) Dimethylformamide (DMF), PropyleneCarbonate (PC) and a combination of any or all of DMSO, DMF or PC, andwherein the solvent has less than 5% water by weight.
 7. The method ofclaim 5, wherein preparing the PAN-based precursor solution includesdissolving the PAN in the solvent via a convective mixing operation at atemperature ranging from 25° C. to 130° C. until the PAN is completelydissolved or for 1 hour to 1 week, wherein the PAN has a molecularweight ranging from 100,000 to 500,000.
 8. The method of claim 1,wherein the mechanical treatment of the post-electro-spinning operationincludes one or both of hot-rolling and/or hot-drawing; and the chemicaltreatment of the post-electro-spinning operation includes dipping theone or more carbon nanofibers in a 5% to 30% hydrogen peroxide solutionfollowed by removing any remaining solvent and/or any remaining hydrogenperoxide from the one or more carbon nanofibers.
 9. The method of claim8, wherein the hot-rolling mechanically compresses the one or morePAN-based nanofibers at temperature ranging from 50° C. to 300° C. and astress ranging from 20 kPa to 2000 kPa; and the hot-drawing stretchesthe one or more carbon nanofibers 5%-50% of an original length of theone or more PAN-based nanofibers.
 10. The method of claim 8, wherein thestabilizing treatment includes heating the one or more PAN-basednanofibers at a temperature ranging from 200° C. to 300° C. whileperforming the mechanical treatment.
 11. The method of claim 1, whereinthe stabilizing treatment includes heating the one or more PAN-basednanofibers at a temperature ranging from 200° C. to 400° C.
 12. Themethod of claim 1, wherein the pyrolysis treatment includes: performingfirst heating operation of the one or more PAN-based nanofibers in theinert atmosphere at temperature between 200° C. to 400° C. for a timeranging from 1 hour to five hours; after the first heating operation,performing a second heating operation of the one or more PAN-basednanofibers in the inert atmosphere at temperature between 600° C. to2000° C. for a time ranging from 1 hour to five hours; and after thesecond heating operation, performing a cooling operation on the one ormore carbonized PAN-based nanofibers to room temperature; wherein atemperature ramp rate for each operation of the pyrolysis treatment doesnot exceed 20° C./minute.
 13. The method of claim 1, wherein the choiceof polymer precursor, the electro-spinning operation and the pyrolysistreatment is sufficient to cause the combined percentage of quaternaryand pyridinic nitrogen groups to exceed 80%.
 14. The method of claim 13,wherein the choice of polymer precursor, the electro-spinning operationand the pyrolysis treatment is sufficient to cause the combinedpercentage of quaternary and pyridinic nitrogen groups to exceed 90%.15. A carbon-based composition; comprising: one or more carbonnanofibers that include a carbon composite, wherein the carbon compositeis a semi-graphitic carbon material characterized by wavy graphiteplanes ranging from 0.1 nm to 1.0 nm and having fringes orientedparallel to an axis of a respective carbon nanofiber, and thesemi-graphitic carbon material is also characterized by an inclusion ofby an inclusion of 4 to 10 atomic percent of nitrogen heteroatoms, thenitrogen heteroatoms including a combined percentage of quaternary andpyridinic nitrogen groups equal to or greater than 60% of the nitrogenheteroatoms.
 16. The carbon-based composition of claim 15, wherein thecombined percentage of quaternary and pyridinic nitrogen groups of thenitrogen heteroatoms exceeds 80%.
 17. The carbon-based composition ofclaim 16, wherein the combined percentage of quaternary and pyridinicnitrogen groups of the nitrogen heteroatoms exceeds 90%.
 18. Acarbon-based composition of one or more carbon nanofibers that include acarbon composite, wherein the carbon composite is a semi-graphiticcarbon material characterized by wavy graphite planes ranging from 0.1nm to 1.0 nm and oriented parallel to an axis of a respective carbonnanofiber, the semi-graphitic carbon material also being characterizedby an inclusion of 4 to 10 atomic percent of nitrogen heteroatoms withthe nitrogen heteroatoms including a combined percentage of quaternaryand pyridinic nitrogen groups equal to or greater than 60% of thenitrogen heteroatoms, wherein the carbon-based composition is preparedby a process comprising the steps of: preparing a Polyacrylonitrile(PAN) based precursor solution; providing the PAN-based precursorsolution to a spinneret; performing an electro-spinning operation on thePAN-based precursor solution to create the one or more carbonnanofibers, wherein the electro-spinning operation includes passing thePAN-based precursor solution from the spinneret to a collector whileproviding an Alternating Current (AC) voltage between the spinneret andthe collector, the AC voltage having a frequency ranging from 20 Hz to100,000 Hz and either a Peak-to-Peak (P-P) voltage ranging from 100 V to30,000 V or a Root-Mean-Square (RMS) voltage ranging from 100 V to30,000 V; performing a post-electro-spinning operation on the one ormore carbon nanofibers, the post-electro-spinning operation including amechanical treatment and a chemical treatment; performing a stabilizingtreatment on the one or more carbon nanofibers, the stabilizingtreatment including heating the one or more carbon nanofibers; and afterperforming the post-electro-spinning operation and stabilizingtreatment, performing a pyrolysis treatment on the one or more carbonnanofibers, the pyrolysis treatment including heating the one or morecarbon nanofibers in an inert atmosphere containing less than 1% oxygen.19. The carbon-based composition of claim 18, wherein the combinedpercentage of quaternary and pyridinic nitrogen groups of the nitrogenheteroatoms exceeds 80%.
 20. The carbon-based composition of claim 19,wherein the combined percentage of quaternary and pyridinic nitrogengroups of the nitrogen heteroatoms exceeds 90%.